#include <stdio.h>

int main(){
    void copy_string(char from[],char to[]);
    char a[]="I am a teacher.";
    char b[]="You are a student.";
    printf("string a=%s\n string b=%s\n",a,b);
    printf("copy string a to string b:\n");
    copy_string(a,b);
    printf("\nstring a=%s\nstring b=%s\n",a,b);
    return 0;
}
void copy_string(char from[],char to[]){
    int i;
    while(from[i]!='\0'){
        to[i]=from[i];
        i++;
    }
    to[i]='\0';
}